Water soluble package

ABSTRACT

A package containing an agrochemical composition which package contains a first sheet of non-planar water soluble or water dispersible material defining a concavity enclosing the agrochemical composition and a second sheet of water soluble or water dispersible material sealed to the first sheet by a continuous closed water soluble or water dispersible seal.

[0001] This invention relates to a water soluble or water dispersiblepackage containing an agrochemical, eg a pesticidal composition, and toa process for producing such a package.

[0002] Agrochemicals include pesticides, e.g. herbicides, which areoften potentially harmful materials and are commonly produced as aconcentrated solution or dispersion in an organic liquid, as a gel or insolid form. Such chemicals are typically supplied in a metal orblow-moulded plastics container. To use chemical pesticides, e.g.herbicides, a quantity of the pesticide is measured out of the containerin concentrated form and then mixed with a large volume of water beforebeing sprayed onto a locus to be treated or onto plants. Suchconcentrated materials are frequently highly toxic so great care must betaken in measuring and mixing them to avoid spillage and to avoid humanor animal contact with the concentrated pesticide.

[0003] Efforts have been devoted to the design of containers to minimisethe risk of accidental spillage of their contents when used and also toreduce residues remaining in the containers after use. Plasticscontainers with wide necks to facilitate pouring of their contents havebeen used. Blow moulded plastics containers having hollow handles havebeen made in which the hollow handles are isolated from the body of thecontainer to avoid retention of material in the handle.

[0004] Nevertheless, with present packages it is relatively easy tospill the contents during the mixing process with the resulting risk ofcontamination of the environment and risk of contact with humans oranimals. Also, it is relatively rare to empty containers so thatfarmers, and other users, tend to have partly full containers leftaround. These represent a further hazard. Even when all of the contentshave been used it is difficult to dispose of the empty container. It isalso difficult to wash adequately the containers and measuringinstruments in which the concentrated pesticides are handled. Thesedevices represent a further hazard to personnel and to the environment.

[0005] It has been proposed to package agricultural chemicals in acontainer comprising a screw fitting adapted to screw onto acorresponding fitting on a spray tank. The contents of the containershould be released only when a satisfactory seal exists between the tankand the container. Practical difficulties exist in securing widespreaduse of such a system in view of the need for standardisation of screwfitting sizes and the possibility of leakage if a satisfactory tightseal is not achieved.

[0006] It has also been proposed to package chemicals in a water solublecontainer which releases the packaged chemical only after contact withwater. Thermoplastic polyvinyl alcohol compositions which are resistantto strong acids are described in European Patent No 155606. Suchapplications have however been limited by the capabilities of knownwater soluble containers which are often too prone to rupture. It hasalso proved difficult to avoid pinholes at heat-sealed joints incontainers leading to leaking of the contents and unacceptable weaknessin the material of the container adjacent to heat sealed joints.

[0007] The present invention seeks to overcome the disadvantages ofknown packages and to provide a package which contains an agrochemicalsuch as a pesticidal composition and has one or more of the followingadvantageous features:

[0008] the packaged chemical is released only after contact with waterin which it is to be dissolved or dispersed, minimising the possibilityof accidental contact of the undiluted material with the environment orwith humans or animals;

[0009] the chemical can be provided in unit dosage form suitable fordilution with a predetermined amount of water removing the need forundiluted chemical to be measured out;

[0010] the packaged chemical is easy to use: the packaged chemical canbe simply placed in water prior to use of the chemicals; and

[0011] the need for washing out of the residual chemical from containersto render them safe for disposal is removed: containers which have beenin contact with the packaged chemical remain uncontaminated whichfacilitates their disposal.

[0012] We have now devised a new package which dissolves in water, maybe cheaply and easily produced and is unexpectedly strong and resistantto rupture or breakage.

[0013] Accordingly the present invention provides a package containingan agrochemical, eg a pesticidal composition, which package comprises afirst sheet of non-planar water soluble or water dispersible materialand a second sheet of water soluble or water-dispersible materialsuperposed on the first sheet and sealed to it by a continuous closedwater soluble or water dispersible seal along a continuous region of thesuperposed sheets. The seal may be produced using a solvent, eg water,or using eg ultrasound but is preferably a heat seal. The continuousregion of the superposed sheets is preferably substantially planar.

[0014] The invention further provides a process for producing such apackage which comprises:

[0015] moulding a first, sheet of water soluble or water dispersiblematerial to form a non-planar sheet comprising at least one recessadapted to retain an agrochemical, eg a pesticidal composition, saidrecess being bounded by a flange, which flange is preferablysubstantially planar;

[0016] placing an agrochemical, eg a pesticidal composition in the atleast one recess;

[0017] placing a second sheet of water soluble or water dispersiblematerial on the flange and across the or every recess; and

[0018] sealing (preferably heat sealing) the first and second sheetsalong the flange to form a continuous closed water soluble or waterdispersible seal.

[0019] The agrochemical may be, for example, a plant protection agent, aplant growth regulator or a plant nutrient. An example of a plantprotection agent is a pesticide (such as an insecticide, fungicide,herbicide, acaricide or nematocide).

[0020] The pesticidal composition may be in liquid form, or solid form,or gel form. It may comprise any conventional carrier or diluent orsurfactant. Where the composition is in liquid form it may be in theform of a solution or of a dispersion in an organic liquid. e.g. anemulsion or a suspension. Similarly in gel form, the composition maycontain pesticide either dissolved or dispersed in the substantially drymedium.

[0021] The packages of the present invention generally contain from 0.1grams to 7 kg, preferably 1 g to 5 kg, where the composition is in solidform. Where the composition is in liquid or gel form, the packagetypically contains from 1 ml to 10 litres, preferably from 0.5 to 5litres (0.1 litres to 1.5 litres is especially preferred); on a smallerscale a range of 5 ml to 1 litre is also useful.

[0022] Generally the package will contain at least a small amount ofspace, eg at least about 5% by volume, so as to minimise the likelihoodof spillage of the composition during the production of the package.

[0023] Particularly when the contents of the package are solid, forexample as a powder or granules, it may be advantageous to ensure thatthe package produced is evacuated of air or the contents are underreduced pressure. The package thus produced has a number of advantages,for example substantially increased resistance to shock. A powder orgranules in such a package is compacted and is, effectively,skin-packaged within the film. Compaction of the product makes thepackage more likely to sink when dropped into water and the packageoccupies less space during storage. Thus, the advantages of packagingunder reduced pressure include:

[0024] a) the absence of gas surrounding the agrochemical compositionreduces the possibility of the package failing for example, at lowtemperatures. Normally at low temperatures, eg close to 0° C., watersoluble plastics films, for example polyvinyl alcohol, forming a packagebecome brittle and therefore the package becomes more likely to fail.Reducing the space in which the agrochemical composition contained bythe package can move about reduces the likelihood of the packagefailing;

[0025] b) where the agrochemical composition is in the form of granules,the likelihood of the granules breaking down into dust within thepackage (which can lead for example to the active ingredientdecomposing) is reduced when the package is skin-tight;

[0026] c) the density of the package can be altered according to theextent to which the package is under reduced pressure. This offersfurther advantages, for example in increasing the speed of dissolutionof the package by ensuring that the package sinks when placed forexample in a spray tank;

[0027] d) where the agrochemical is a particulate solid which does notcomprise a binding agent, such as a plasticiser, it may be advantageousfor the package to hold the agrochemical substantially rigid within thepackage to prevent segregation and possible decomposition of theagrochemical (which may be incompatible with certain plasticisers: theplasticiser in the agrochemical may also be incompatible with the film).

[0028] Typically the two sheets of water soluble or water dispersiblematerial are of the same material, but they may be different. One sheetof the water soluble or water dispersible material may be easy to printupon.

[0029] When the pesticidal composition is in liquid or gel form andcomprises an organic solvent the water soluble or water dispersiblematerial will be one which is insoluble in the organic solvent.

[0030] Suitable water soluble or dispersible materials are polyethyleneoxide and methyl cellulose. More preferably a polyvinyl alcohol (PVOH)film is used. Such a PVOH film may be a partially or fully alcoholisedor hydrolysed e.g. 40-99%, preferably 70-92% alcoholised or hydrolysed,polyvinyl acetate film. The film may be a cast film or, more preferably,a blown or extruded film.

[0031] The polyvinyl alcohol film may be unoriented, monoaxiallyoriented or bi-axially oriented. Water soluble materials are preferredsince they provide less disposal problems. The materials used willgenerally be cold water soluble; cold water soluble polyvinyl alcohol ispreferred. It will be understood that other materials may be used whenthe package is to be dissolved or dispersed in water or hot water.Generally the water soluble or water dispersible material will beflexible.

[0032] The maximum tensile strength of the material of the envelope ispreferably at least 20, more preferably from 30 to 80, N/mm² and may beas much as 200 N/mm² or more; and the elongation at break is preferably200 to 380%, more preferably from 220 to 350% and may be as much as 500per cent or more. Testing for these values is generally carried out at23° C. and 50% relative humidity.

[0033] When the pesticidal composition is in liquid or gel form it isparticularly important to avoid pinholes in the package through whichleakage of the composition may occur. In such cases therefore the watersoluble or water dispersible material will typically be a laminate,generally of two layers of different or preferably the same watersoluble or water dispersible material, as pinholes are unlikely tocoincide in two layers of material. Typically the laminates will consistof 2 layers of thickness from 20 μm to 1 mm, preferably about 40 μm,each. Generally however the thickness of the layers will be kept to theminimum needed to prevent rupture of the package, so that the watersoluble or dispersible material is dissolved or dispersed as quickly aspossible and the pesticide then released.

[0034] When the pesticidal composition is in solid form, the sheets ofwater soluble or water dispersible material typically comprise a singlelayer of material. In such case the material will generally be from 20to 500 μm, preferably 30 to 100 μm, thick. However, in cases where it isparticularly desirable to avoid pinholes in the package, eg. to preventthe escape of unpleasant odours, a laminate material of the typedescribed above may be used. As with packages containing liquids andgels, the thickness of the water soluble dispersible material willgenerally be kept to a minimum in packages containing solidcompositions.

[0035] When the packages are produced by thermoforming, as is preferred,the thickness of the first sheet will generally not be less than 20μ and(to maintain ease of processing) generally not more than 1 mm. Apreferred range is from 80-400μ, eg 100-400μ, most preferably about250μ.

[0036] The thickness of the second sheet may be less than that of thefirst sheet as the second sheet will not generally be thermoformed sothat localised thinning of the sheet will not occur. The thickness ofthe second sheet will generally not be less than 10μ, preferably notless than 20μ. For ease of processing the film will generally not bemore than 1 mm thick, a preferred range being from 20μ to 250μ, mostpreferably about 150μ.

[0037] In a particular embodiment the package is provided with a regionwhich will more readily dissolve in water than the rest of the package.This offers advantages, for example by speeding up the dispersion of theagrochemical contained in the package. The region may be provided forexample by making one sheet of the water-soluble or water dispersiblematerial thinner than the other, or by making one portion of the packagethinner than the rest.

[0038] In the packages of the present invention, the package does notpossess a seam running down the centre of one of the faces of thepackage. This offers advantages over known packages, for example byreducing the likelihood of failure occurring in the package when it issubjected to shock, because packages having a seam running down thecentre of one of the faces of the packages necessarily have a point atwhich two or more seals intersect which will be more likely to failunder shock than the equivalent package not having this point ofintersection.

[0039] The two water soluble or water dispersible sheets in the packagesare sealed together by a closed continuous heat seal. Typically toensure that the seal is water soluble and does not suffer from leakage,it is a single continuous seal and has no geometrical discontinuities,i.e. it does not comprise any angular intersections with itself.Therefore the heat seal will usually be curved, at least in portions,for instance at the corners of the package: the radius of curvature ofthe heat seal will generally not be less than 1 mm, preferably not lessthan 5 mm, and not more than half the width of the package.

[0040] Suitable pesticides which may be used in the package of thepresent invention include fungicides, insecticides and herbicides (forexample hydroxybenzonitrile herbicides, e.g. bromoxynil or ioxynil orderivatives thereof such as salts or esters, e.g. heptanoates oroctanoates). Molluscicides, suitable for addition to, for example, pondsor streams may also be employed.

[0041] The invention is not limited to specific agrochemicals.Agrochemicals which can be used in the invention include:

[0042] Fungicides such as Triadimefon, Tebuconazole, Prochloraz,Triforine, Tridemorph, Propiconazole, Pirimicarb, Iprodione, Metalaxyl,Bitertanol, Iprobenfos, Flusilazole, Fosetyl, Propyzamide,Chlorothalonil, Dichlone, Mancozeb, Anthraquinone, Maneb, Vinclozolin,Fenarimol, Bendiocarb, Captafol, Benalaxyl, Thiram, Captan, Fosetyl-Al,Zineb, Sulfur, Quintozene, Copper salts, Thiophanate-methyl,Tricyclazole, Dichloran, Chloroneb, Cyproconazole, Hexaconazole,Imazalil, Dodine, Diniconazole, Guazatine, Thiabendazole, Carboxin,Ferban, Glyodin, Fentin (triphenyltin), Terrachlor, Terrazole andBenomyl;

[0043] Herbicides (or defoliants) such as quizalofop and itsderivatives, Acetochlor, Metolachlor, Imazapur and Imazapyr, Glyposateand Gluphosinate, Butachlor, Acifluorfen or Acifluorfen-sodium,Oxyfluorfen, Butralin, Fluazifop-butyl, Bifenox, Bromoxynil and Ioxyniland esters thereof, Diflufenican, Phenmedipham, Desmedipham, Oxadiazon,Mecoprop MCPA, MCPB, Linuron, Isoproturon, Flamprop and its derivatives,Ethofumesate, Diallate, Carbetamide, Alachlor, Chorpyralid, 2,4-D,Tribufos, Triclopyr, Diclofop-methyl, Sethoxydim, Pendimethalin,Trifluralin, Ametryn, Chloramben, Amitrole, Asulam, Dicamba, Bentazone,Atrazine, Cyanazin, Thi

Prometryn, 2-(2-chlorobenzyl)-4,4-dimethyl-1,2-oxazolidin-3-one,Fluometuron, Napropamide, Paraquat, Bentazone, Molinate, Propachlor,Imizaquin, Metribuzin, Tebuthiuron, Oryzalin, Pursuit, Norflurazon,Simazine, Linuron, Trichlopyr, Aclonifen, Flurtamone, Sulfonylureas egNicosulfuron, Chlorsulfuron, Sulfometuron-methyl, Metsulfuron-methyl,Bensulfuron-methyl, Chlorimuron-ethyl, Tribenuron-methyl,Thifensulfuron-methyl, Primisulfuron-methyl, Ethametsulfuron-methyl andRimsulfuron,and Trialkoxydim and

[0044] Insecticides, miticides, acaricides or nematicides such asEbufos, Carbosulfan, Amitraz, Vamidothion, Ethion, Triazophos, Propoxur,Phosalone, Permethrin, Cypermethrin, Parathion, Methylparathion,Diazinon, Metomyl, Malathion, Lindane, Fenvalerate, Ethoprophos, Endrin,Endosulfan, Dimethoate, Dieldrin, Dicrotophos, Dichloroprop, Dichlorvos,Azinophos and its derivatives, eg Azinophos-methyl, Aldrin, Cyfluthrin,Deltamethrin, Disulfoton, Chlordimeform, Chloropyrifos, Carbaryl,Dicofol, Thiodicarb, Propargite, Demeton, Phosalone, Acephate,Carbofuran, Methamidophos, Fenbutalin oxide, Trichlorfon, Abamectin,Aldicarb, Pyrethroids such as alpha-Cypermethrin and Bacillusthuringiensis.

[0045] Plant growth regulators such as gibberellic acid, ethrel orethephon, cycocel, Chlormequat, Mephiquat, Thiadiazuron, Tribufos andDimethipin.

[0046] Where the pesticidal composition is in liquid form then suitableorganic solvents which may be used as carriers in the pesticidalcomposition include petroleum based solvents, e.g. petroleum ethers,mineral oils, aliphatic or aromatic hydrocarbons, e.g. hexane, octane,cyclohexane, benzene, xylene and naphthalene, halogenated aliphatic oraromatic hydrocarbons, e.g. carbon tetrachloride, chloroform, methylenechloride and chlorobenzene, esters e.g. amyl acetate, ketones, e.g.cyclohexanone, 1-methyl-2-pyrrolidinone (NMP), ethers, or a higheralcohol (lower alcohols may migrate through the water soluble or waterdispersible materials described above: this can result in productappearing on the outside of the envelope). It will be understood thatmixtures of solvents, e.g. mixtures of a hydrocarbon solvent withanother solvent such as a ketone or a higher alcohol, may also be used.The organic liquid must be reasonably dry and typically contains lessthan 2 to 3% of water to ensure that it does not leak prematurely fromthe package.

[0047] Such compositions may comprise, in addition to, or in some casesinstead of, an organic solvent as a carrier or diluent, a surfactant,which is reasonably dry in that it contains less than 2 to 3% water.Suitable surfactants may be of the ionic or non-ionic types: for examplesulphoricinoleates, quaternary ammonium derivatives, products based oncondensates of ethylene oxide with alkyl and polyaryl phenols, e.g.nonyl- or octyl-phenols, or carboxylic acid esters of anhydrosorbitolswhich have been rendered soluble by etherification of the free hydroxygroups by condensation with ethylene oxide, alkali and alkaline earthmetal salts of sulphuric acid esters and sulphonic acids such asdinonyl- and dioctyl-sodium sulphonosuccinates and alkali and alkalineearth metal salts of high molecular weight sulphonic acid derivativessuch as sodium and calcium lignosulphonates and sodium and calciumalkylbenzene sulphonates, and block ethylene oxide/propylene oxidecopolymers.

[0048] Suitably, the pesticidal composition may comprise up to 10%, e.g.from 0.05% to 10% of surfactant but, if desired, it may comprise higherproportions of surfactant for example up to 15% in liquid emulsifiablesuspension concentrates and up to 25% in water soluble concentrates.

[0049] The contents of the package may be thickened or renderedthixotropic to provide a gel. An increased viscosity in the contents canreduce the likelihood of rupture if the package is subjected tomechanical shock. The contents of the package may be rendered moreviscous or thixotropic by the inclusion of additives, for example, amodified organophile, or bentonite, lecithin, polymethylene oxide orsilica gel.

[0050] The concentrations of pesticide or herbicide dissolved ordispersed in the organic liquid or in the gel will generally be thoseconventionally used: in order to reduce the bulk of each package,however, concentrations may be increased. Each package will preferablycontain 100 ml to 1.5 litres, preferably at least about 500 ml and willpreferably contain a convenient standard volume, for example 500 ml or 1litre, although it will be appreciated that any convenient standardvolume may be chosen.

[0051] When the pesticidal composition is in solid form then it maycomprise any conventional carrier or diluent which is reasonably dry, inthat it contains less than 2 to 3% of moisture. Examples of suitablesolid diluents or carriers are aluminium silicate, talc, calcinedmagnesia, kieselguhr, tricalcium phosphate, powdered cork, adsorbentcarbon black and clays such as kaolin and bentonite. Solid compositionsmay comprise surfactants, such as dispersing agents, for example thosesurfactants previously mentioned. In some cases such surfactants mayalso be used as diluents or carriers.

[0052] As with compositions in liquid form, the concentration ofpesticide in the solid pesticidal compositions may be as conventionallyused: concentrations may however be increased to reduce the bulk of thepackage.

[0053] The pesticidal compositions used in the package of the presentinvention may be prepared by conventional means.

[0054] The packages of the present invention may be inside an additionalouter container. Such a container may provide additional strength and ifwater resistant may serve to protect the package of the presentinvention from accidental exposure to water. The outer container ispreferably sealed to avoid exposing the package of the present inventionto undue moisture.

[0055] It will be appreciated that the package of the present inventionmay comprise more than one compartment containing the same or differentpesticidal compositions. Such multi-compartment packages areparticularly useful where a combination of components are to be employedtogether and where the components are incompatible for a prolongedperiod, for instance if they react chemically.

[0056] Preferably the packages according to the invention should releasetheir contents in less than about 10 minutes. Typically the packageswill be placed in the spray tank of a conventional sprayer. The tankwill generally be partly filled with water, and the package added. Whenthe tank is provided with means to agitate the water the contents of thebag will be released more rapidly. It is preferred that release shouldtake place in less than about a minute, for example in 30 to 40 seconds.It will be understood that the time taken to release the pesticide willdepend upon a number of factors apart from the nature of the bag,including the temperature of the water and the level of agitation.

[0057] The packages of the present invention may be obtained by firstdeforming a sheet of water soluble or dispersible material so as to forma recess adapted to retain a pesticidal composition. This may beachieved for example by vacuum forming where the sheet is deformed toconform to the shape of a suitable mould and may, if desired, be athermoforming process to cause the sheet to retain its shape afterrelease from the mould.

[0058] Where the deformation is by vacuum forming, the mould may beequipped with pinholes through which the space between the mould and thesheet can be evacuated.

[0059] Where deformation is by thermoforming, the sheet may be drivenagainst the mould by vacuum forming, or by applying a superatmosphericpressure to the other side of the sheet (this may be effected using anoperating pressure of, for example 4½ to 6 bar) or by mechanicaldisplacement of the sheet (plug forming). Thermoforming will generallybe carried out using a temperature not less than 40° C. and not morethan 110° C. A temperature from 70-110° C. is preferred, most preferablyabout 90° C.

[0060] After deforming the first sheet of water soluble or dispersiblematerial, the pesticidal composition is placed in the recess formed bythe deformation, and a second substantially planar sheet of watersoluble or water dispersible material is then placed across the recess.The two sheets of water soluble or water dispersible material are thenheat sealed so as to form a continuous closed heat seal. The width ofthe heat seal itself is preferably 1-10 mm, preferably about 5 mm. Thedwell time for heat sealing will depend upon, for example, the materialused, its thickness and the heat seal temperature. A dwell time of about3 seconds is generally suitable when the thickness of the material isabout 80μ. A sealed compartment is thus formed.

[0061] In order to ensure optimum processability the heat sealing isgenerally carried out at 15 to 25° C. and 15 to 85% relative humidity(RH). The relative humidity is preferably 35 to 55%. Some routineexperimentation may be required to obtain a suitable heat seal dependingon the package material, e.g. the particular grade and thickness of PVOHchosen. The quality of the seal can be checked, for example by visualinspection for areas of opacity or for bubbles. Imperfections in theseal may give rise to a lack of water solubility or water dispersibilityof the seal. The heat sealing process can be carried out on conventionalheat sealing equipment which permits control variation of the sealingjaw temperature, jaw pressure and dwell time.

[0062] The following Examples illustrate the invention. In the Examplesthe values for tensile strength refer to a seal of 25 mm width with ajaw separation speed of 300 mm/min.

EXAMPLE 1

[0063] A first sheet of polyvinyl alcohol (Vinex 2144: thickness 225μ)is heated at 90° C. and then thermoformed into a mould, the draw depthbeing 80 mm, with a forming time of 6 seconds. The product to bepackaged is placed in the recess thus formed. A second sheet ofpolyvinyl alcohol (Solublon KA40/KA40, a laminate of two layers each of40μ thickness: total thickness 80μ) is placed across the recess thusformed and heat sealed using a sealing temperature of 180° C. with adwell time of 8 seconds. The operating air pressure of the thermoformingapparatus is 4.5 bar.

[0064] The tensile strength of the seal in the water-soluble bags thusproduced is 32.4 N (mean). The production of the water-soluble bags iscarried out at 21° C. (room temperature) and a relative humidity of 38%.

EXAMPLE 2

[0065] A first sheet of polyvinyl alcohol (Vinex 2144: thickness 225μ)is heated at 90° C. and then thermoformed into a mould, the draw depthbeing 80 mm, with a forming time of 6 seconds. The product to bepackaged is placed in the recess thus formed. A second sheet ofpolyvinyl alcohol (Vinex 2144: thickness 75μ) is placed across therecess thus formed and heat sealed using a sealing temperature of 200°C. with a dwell time of 6 seconds. The operating air pressure of thethermoforming apparatus is 4.5 bar.

[0066] The tensile strength of the seal in the water-soluble bags thusproduced is 28.7 N (mean). The production of the water-soluble bags iscarried out at 21° C. (room temperature) and a relative humidity of 38%.

1. A package containing an agrochemical which package comprises a firstsheet of non-planar water soluble or water dispersible material and asecond sheet of water soluble or water dispersible material superposedon the first sheet and sealed to it by a continuous closed water solubleor water dispersible seal along a continuous region of the superposedsheets.
 2. A package according to claim 1 wherein the agrochemical is aplant protection agent, a plant growth regulator or a plant nutrient. 3.A package according to claim 1 wherein the agrochemical is a pesticide.4. A package according to claim 1 wherein the agrochemical is aninsecticide, fungicide, herbicide, acaricide or nematocide.
 5. A packageaccording to any one of the preceding claims wherein the water solubleseal is a water soluble heat seal.
 6. A package according to any one ofthe preceding claims wherein the second sheet is sealed to the firstsheet along a substantially planar continuous region of the superposedsheets.
 7. A package according to any one of the preceding claimswherein the first and second sheets are made of the same material.
 8. Apackage according to claim 7 in which the first and second sheets eachcomprise a laminate of at least two layers of water soluble or waterdispersible material.
 9. A package according to claim 8 which comprisestwo layers each having a thickness from 20 μm to 1 mm.
 10. A packageaccording to any one of the preceding claims in which the pesticidalcomposition is in liquid or gel form.
 11. A package according to any oneof claims 1 to 7 containing a pesticidal composition in solid form inwhich each of the first and second sheets comprises a single layer ofwater soluble or water dispersible material.
 12. A package according toclaim 11 in which the sheet has a thickness from 20 to 500 μm.
 13. Apackage according to any one of the preceding claims which contains from1 ml to 10 litres of pesticidal composition in liquid or gel form orfrom 0.1 grams to 7 kg of pesticidal composition in solid form.
 14. Apackage according to any one of claims 1 to 13 which contains from 0.1litres to 1.5 litres of agrochemical composition in liquid or gel form.15. A package according to any one of the preceding claims in which theheat seal is a single continuous seal not comprising any angularintersections with itself.
 16. A package according to any one of claims1 to 14 wherein the seal is curved.
 17. A package according to any oneof claims 1 to 14 wherein the seal is curved, with the radius ofcurvature of the seal being from 1 mm to half the width of the package.18. A package according to any one of claims 1 to 14 wherein the seal iscurved, with the radius of curvature of the seal being from 5 mm to halfthe width of the package.
 19. A package according to any one of thepreceding claims in which the water soluble or dispersible materialcomprises polyethylene oxide, methyl cellulose or a polyvinyl alcohol.20. A package according to claim 19 in which the water soluble or waterdispersible material comprises a cold water soluble polyvinyl alcoholwhich is 40 to 99% hydrolysed or alcoholised polyvinyl acetate.
 21. Apackage according to any one of the preceding claims in which thecontents are released in less than 10 minutes after contact with water.22. A package according to claim 21 in which the contents are releasedin less than 1 minute.
 23. A package according to any one of thepreceding claims which comprises a region which will more readilydissolve than the rest of the package.
 24. A package according to anyone of the preceding claims in which the chemical comprises ahydroxybenzonitrile herbicide.
 25. A package according to claim 24, inwhich the hydroxybenzonitrile herbicide comprises a mixture of ioxyniland bromoxynil esters.
 26. A process for producing a package as claimedin any one of the preceding claims which comprises: moulding a firstsheet of water soluble or water dispersible material to form anon-planar sheet comprising at least one recess adapted to retain anagrochemical composition, said recess being bounded by a flange; placingan agrochemical composition in the at least one recess; placing a secondsheet of water soluble or water dispersible material on the flange andacross the or every recess; and sealing the first and second sheetsalong the flange to form a continuous water soluble or water dispersibleseal.
 27. A process according to claim 26 in which the recess is boundedby a substantially planar flange.
 28. A process according to claim 26 or27 in which the sealing of the first and second sheets is effected byheat sealing.
 29. A process according to claim 26, 27 or 28 in which thefirst water soluble or water dispersible sheet is deformed byvacuum-forming to conform to a mould.
 30. A process according to claim26, 27 or 28 wherein the first water soluble or water dispersible sheetis deformed by thermo-forming.
 31. A process according to any one ofclaims 26 to 30, in which the first and second sheets are heat sealed ata sealing temperature of from 140 to 220° C.
 32. A process according toany one of claims 26 to 31 in which the first and second sheets are heatsealed at a sealing jaw pressure from 1×10⁻⁴ to 3.5×10⁻⁴ kg/m².
 33. Aprocess according to any one of claims 26 to 32 in which the first andsecond sheets are heat sealed with a dwell time from 0.2 to 1.5 seconds.34. A process according to any one of claims 26 to 33 in which the firstand second sheets are heat sealed at a relative humidity from 15 to 85%.35. A package according to claim 1 and substantially as hereinbeforedescribed.
 36. A process according to claim 26 and substantially ashereinbefore described.